Lichrospher 100 rp 18 endcapped

HPLC analysis was conducted using a Waters 2690 Alliance Separation Module with a LiChrospher® 100 RP-18 endcapped Merck column cartridge (250 × 4.6 mm, 5 μm). For the gradient flows used for gallic acid and catechin, the two-solvent system (solvent A: 0.1% formic acid in water; solvent B: 0.06% formic acid in water) was as follows: 0 min: 95% A, 5% B; 10 min: 80% A, 20% B; 22 min: 80% A, 20% B, which was held until the end. For andrographolide, methanol : water (60 : 40) was used; for rosmarinic acid, 0.5% phosphoric acid in water and acetonitrile (60 : 40) were used; and for curcumin, 5% acetic acid in water and acetonitrile (50 : 50) were used. The flow rate for all mobile phases was 1.0 mL min⁻¹. The chromatograms were monitored at wavelengths of 340 nm (rosmarinic acid), 272 nm (gallic acid), 223 nm (andrographolide), 280 nm (catechin), and 428 nm (curcumin).